Gas driven hydraulic pump



Feb. 6, 1962 J. D. MOELLER ET AL GAS DRIVEN HYDRAULIC PUMP Original Filed May 9, 1958 3 Sheets-Sheet 1 INVENTORS Jomv D MOELLER THEIR ATTORNEY Feb. 6, 1962 J. D. MOELLER ETAL 3,019,735

GAS DRIVEN HYDRAULIC PUMP Original Filed May 9, 1958 3 Sheets-Sheet 2 110 m 170 I68 11: l

Z INVENTORS JOHN D. Mosum 7'50 R. SCARFF THEIR ATTORNEY Feb. 6, 1962 o L- E 3,019,735

GAS DRIVEN HYDRAULIC PUMP Original Filed May 9, 1958 3 Sheets-Sheet 5 JOHN D. OELLER BY 750 A. ScARFF THEIR ATTORNEY 3,019,735 GAS DRIVEN HYDRAULIC PUMP John D. Mueller, Dayton, and Ted R. Scartf, Troy, Ohio, assigncrs to General Motors Corporation, Detroit, Mich, a corporation of Delaware Original application May 9, 1958, Ser. No. 734,185, new Patent No. 2,942,553, dated June 28, 1960. Divided and this application Oct. 5, 1959, Ser. No. 847,859

4 Claims. (Cl. 103-49) ire States atent type gas driven hydraulic pump; the further provision of 1 an inertia balanced reciprocating gas drivenihydraulic pump; and thestill further provision of "a partial admission reciprocating gas driven hydraulic pump.

The aforementioned and other objects are accomplishe in the present invention'by employing opposed reciprocating piston assemblies which are interconnected for movement in the same directions, and valve means controlled by the pistons for controlling the admission of gas to opposite cylinders so as to maintain the pistons in a state of continuous reciprocation. Specifically, in all of the embodiments disclosed herein the motor and pumping pistons are formed as an integral assembly, and the diameter of the motor pistons is twice the diameter of the pumping pistons. Each motor and pumping piston assembly is mounted for reciprocation in a cylinder having a stepped bore, and the combined motor and piston assemblies are interconnected by a plurality of rods so as to move simultaneously in the same direction. One of the interconnecting rods has a saddle, or valve actuator, thereon for actuating one or the other of a pair of pilot valves adjacent the stroke ends of the two motor and pumping piston assemblies. 7

Gas from any suitable source, such as a solid fuel propellant tank, is supplied to a servo actuated reversing valve. The supply gas pressure is controlled by a relief valve so as to maintain it within predetermined limits, i.e., between 700 and 800 psi. The reversing valve controls the admission and exhaust of gas to the motor chambers, and the position of the reversing valve is controlled by the mechanically and servo actuated pilot valves. r

The pumping chambers are connected by passages through suitable one-way inlet check valves to a reservoir of hydraulic fluid, and likewise connected by passages through one-way outlet check valves to a delivery conduit. The hydraulic pressure in the delivery conduit may be controlled by any suitable pressure regulating valve. In the full admission embodiment, the hydraulic fluid will be discharged at a pressure directly proportional to the ratio between the areas of the pumping and motor pistons, and thus with a supply gas pressure between 700 and 800 p,s.i., the delivery pressure of the pumps will be between 2800 and 3200 psi.

In the partial admission hydraulic pumping system, an

additional servo actuated shuttle valve is incorporated in the system, which shuttle valve is actuated by a predetermined movement of the motor pistons so as to interrupt the supply of gas under pressure to the motor chamber and thereafter allow the gas in the motor chamber to expand. thereby reducing the pressure thereof. In the par- 2 tial admission system, a gas supply having a higher pressure can be utilized to obtain the same pressure in the hydraulic fluid delivery conduit as in the full admission system using a lower gas supply pressure.

In a third embodiment, a second pair of motor and pumping pistons are actuated in an opposite direction to the first set of motor and pumping pistons so as to balance out the inertia effects of the reciprocating system. In this instance, the combined outputs of the pumps are connected in parallel, and movement of the second set of motor and pumping pistons is controlled by the first set of motor and pumping pistons.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein preferred embodiments of the present invention are clearly shown, and wherein similar numerals represent similar parts throughout the several views.

In the drawings:

FIGURE 1 is a schematic view of a'gas actuated reciprocating pump constructed according to oneembodiment of this invention. 1 v I FIGURE 2 is a schematic view similar to FIGURE 1 pumping system. i p

FIGURE 3 is a schematic view illustrating the inertia balance gas actuated pumping system. v

With particular reference to FIGURE 1, the pump illustrating the partial admission gas actuated hydraulic -mechanism comprises a pair of opposed cylinders 10 and 26 of stepped diameter. The cylinders 19 and 20 contain piston assemblies 12 and 22, respectively. The piston 12 has head portions '14 and 16 which are received in the stepped diameter bore of the cylinder 10-, and the piston 22 has head portions 24 and 26 received in the stepped diameter bore of cylinder 20. The piston assemblies 12 and 22 divide-their respective cylinders into motor chambers 18 and 2S and pumping chambers 19 and 29, respectively. Moreover, in the disclosed embodiments, the diameter of the piston head portions 14 and 24 is twice the diameter of the piston head portions 16 and 26 whereby the pressure in the pumpingchambers 19 and 29 will be four times the pressurse in the motor chambers 18 and 28, respectively. 7

The pumping chamber 19 is connected by a passage 30 to a one-way inlet check valve 32. The pumping chamber 29 is connected by a passage 34 with a one-way inlet check valve 36. The inlet sides of the check valves 32 and 36 communicate with a conduit 38 which is connected to a suitable reservoir of hydraulic fluid, not shown. The pumping chambers 19 and 29 are connected to passages 40 and 42, respectively, which connect with one-way outlet check valves 44 and 46. The outlet sides of the check valves 44 and 46 are connected to a conduit 48 which constitutes a delivery conduit ofhydraulic fluid to be supplied to the system. The pressure of the hydraulic fluid in the conduit 48 is determined by a pressure regulator valve 50 which is operable to maintain a substantially constant pressure of hydraulic fluid at the outlet thereof. I

The motor piston heads 14 and 24 are interconnected by a plurality of circumferentially spaced rods 52 so that the pistons move simultaneously in the same direction. The rods 52 are attached to the piston heads and extend through passages 54 and 56 so that the back sides of the motor. piston heads 14 and 24 are connected to exhaust chamber 58 at all times. In addition, one of the rods 52 has attached thereto a valve actuator 60 comprising a a T-shaped member for mechanically operating a pair of reciprocating pilot valves 52 and 64. The pilot valves 62 and 64 are supported for reciprocable movement in valve guides 66. and 68, respectively, having shoulders 67 and 69 which limit inward movement of the pilot valves.

The pivot valve 62 has three axially spaced lauds 70, 72 and 74 and an actuating rod end portion 78. Y The pilot valve 64 likewise has three axially spaced lands 80, 82 and 184 and an axially extending rod portion 38. The rod 36 of the pilot valve 64 can be engaged by end 63 of the valve actuator 60 adjacent the stroke end of the piston 12. The rod 78 of the pilot valve 62 can be engaged by end 61 of the actuator 60 adjacent the .strokeend of the piston 22.

Gas from any suitable source for actuating the motor pistons is supplied through conduit 90, the pressure of the gas being controlled by a relief valve 92, the outlet side of which is connected to an exhaust conduit 93. The

conduit 90 connects with an inlet port 96 of a reversing cate at all times with the annular grooves between lands 98 and 100, and lands 100 and 102, respectively. The port 104 is connected to a passage 108 which communicates with the motor chamber 18. The control port 106 is connected to a conduit 110 that connects with the motor chamber 28.

Branch passages 112 and 114 communicate with the conduit'90, and terminate in ports 116 and 118, respectively, of the pilot valves 62 and 64. The reversing valve 94 also includes exhaust ports 1 20 and 122 which connect with an exhaust passage 125. The exhaust gas passage 125 communicates at all times with the chamber 53 as well as with ports 124 and 126 of the pilot valves 62 and 64, respectively. The pilot valves 62 and 64 also include ports 128 and 130 respectively, which are connected to passages 132 and 134, respectively.

The passage 132 connects with a passage 136. One end of passage 136 connects with the left-hand end of the valve guide 96, and the other end of the passage 136 connects with the right-hand end of the valve guide 68. The passage 13-4 connects with a passage 138. One end of the passage 138 connects with the right-hand end of the valve guide 96, and the other end of the passage 138 connects with the left-hand end of the valve guide 66. Accordingly, when the left-hand end of the valve guide 96 is subjected to pressure so as to move the reversing valve 94 to the position shown in FIGURE 1, the rightvhand end of the valve guide 68 will be subjected to the same pressure so as to move the. pilot valve 64 to the position shown in FIGURE 1 wherein land 84 engages shoulder 69. At this time, the passage 138 is connected toexhaust through ports 130 and 126.

Operation of the pump system disclosed in FIGURE 1 is as follows. With gas under a pressure of between 700 and 800 p.s.i. being supplied to inlet conduit 90, this gas. will .flow through the supply port 95 of the reversing valve 94. The relief valve 92 may be calibrated to open at 750 p.s.i. so that when the pressure of the incoming gas exceeds 750 p.s.i., the relief valve 92 will .open and by-pass a portion thereof to the exhaust conduit 93. With the reversing valve 94 in the position of FIGURE 1, the gas under pressure will flow through supply port 95 to control port 104 and thence througt passage 108 to the motor chamber 18. The piston assembly 12 will move to the right as viewed in FIGURE 1 thereby effecting movement of the piston assembly 22 to the right through the rods 52. Hydraulic fluid which is previously drawn into the pumping chamber 19 through inlet check valve 32 will be delivered through the passage 40 and the outlet check valve 44 to the delivery conduit 48. Since the pressure of the actuati'ng gas remains substantially constant, and since the FIGURE '1.

area of the piston head 14 is four times the area of the piston head 16, the hydraulic fluid will be delivered at a pressure of substantially 3000 p.s.i. With the reversing valve 94 in the position of FIGURE 1, the motor chamber 28 is connected to exhaust through passage 110, ports 106 and 122 and the passage 125. During movements of the piston assembly 22 to the right, the pumping chamber 29 will be expanded and thereby draw hydraulic fluid from inlet conduit 38 through check valve 36 and passage 34 into the pumping chamber 29.

During the power stroke of the piston assembly 12 to the right, the end 63 of the valve actuator 60 will engagethe end 88 of the pilot valve 64 as shown in During continued movement of the piston assembly 12 to the right, the pilot valve 64 will be moved to the right so that at the stroke end of the piston assembly 12 the ports 118 and 130 will be interconnected by the annular groove between lands 32 and 34. Movement of the pilot valve 64 to a position wherein ports 11% and 136 are interconnected will direct incoming gas under pressure from passage 114 through ports 118 and 130 to passage 134. This gas will flow through passage 138 and act on the end surface 103 of the reversing valve to move the reversing valve .94 to the left so as to interconnect ports Y and 106 and connect port 104 to the exhaust port 120. At. the same time, gas under pressure will act through passages 134 and 138 on the end face of land 70 of the pilot valve 62 so as to move the pilot valve 62 to the right as viewed in FIGURE 1 until land 74 engages holder 67. The pilot valve 62 will be moved to a position wherein ports 128 and 124 are interconnected and port 116 is blocked by land 72. In this manner, the left-hand end of the valve guide 96 will be connected to exhaust through passages 136 and 132 and ports 128 and 124.

When the reversing valve 94 has moved to the left, gas under pressure will be supplied through ports 95 and 106 to the passage to the motor chamber 28, and at the same time the motor chamber 18 will be connected to exhaust through passage 108 and ports 104 and 120. Accordingly, the piston units 22 and 12 will move to the left thereby completing the delivery stroke of the pumping piston 26; and effecting the intake stroke of the pumping piston 16. The pistons 12 and 22 will be maintained in a state of continuous reciprocation as long as gas under pressure is supplied to the inlet conduit 90 and hydraulic fluid pumped by the pumping pistons 16 and 26 is used by the system connected with the delivery conduit 98. If the hydraulic system connected to the conduit '48 does not require any flow, movement of the pistons willcontinue at a rate sufiicient to maintain the system pressure. The pressure regulating valve 50 will maintain a pressure of substantially 3000 p.s.i. in the system and dump the excess pump flow to drain.

With particular reference to FIGURE 2, a modified gas driven hydraulic pump is disclosed for use in systems wherein the gas supply is under a higher pressure, for instance 1000 p.s.i. The system disclosed in FIGURE 2 is of the partial admission type, and thus the motor chambers 18 and 28 are formed with ports 140 and 142,

respectively, which connect with passages 144 and 146. The passage 144 connects with an auxiliary port 148 of the reversing valve 94 as well as with a port 150 of a spring centered shuttle valve 152. .The passage 146 connects with an auxiliary port 154 and the reversing valve 94 and a port 156 of the shuttle valve 152. The shuttle valve 152 is formed with an axially spaced lands 158, 160 and 162 as well as oppositely extending rod portions 164 and 16:6. The rod portion 164 is engageable with an abutment 168 which is biased to the right as viewed in FIG- URE 2, by a coil spring 170. The rod portion 166 is engageable. with an abutment 172 which is biased to the left, as viewed in FIGURE 2, by a spring 173. The springs and '173 are disposed in chambers 174 and am y 176 respectively, which are connected to the exhaust con-- duit 125.

The ports 140 and 142 in the motor chambers 18 and 28 are located so that they will be opened by their respective motor pistons 14 and 24 when the power pistons have completed approximately 80% of their power stroke movement. Accordingly,"if gas is supplied through conduit 90 at 1000 p.s.i. to the motor chamber 18, upon opening'of the port 140 gas will be supplied to passage 144 and will act on the end surface of land 158 to move the shuttle valve 152 to the position of FIGURE 2. This movement of the shuttle valve 152 will block the passage 108 thereby cutting 011 further admission of the gas to the motor chamber 18. The gas in motor chamber 18 will now expand to complete the stroke of the power piston 14 so that at the end of its power stroke the pressure in chamber 18 may be on the order of 800 p.s.i. At the end of the stroke of the motor piston 14, the valve actuator '60 will move the pilot valve 64 to a position wherein ports 118 and 130 are interconnected to thereby effect movement of the reversing valve 94 to the left so that gas under pressure will be supplied to the motor chamber 28 while the motor chamber 18 is connected to exhaust. This movement of the reversing valve will also connect port 150 to exhaust through port 148. The motor piston 24 will then effect the delivery stroke of the pumping piston 26 and the intake stroke of the pumping piston 16. When the port 142 is uncovered, gas will be supplied through passage 146 and port 156 to act on the end of land 162. In this manner the shuttle valve 152 will be moved to the left so that land 162 will block the passage 110 whereupon the gas in motor chamber 28 will expand thereby automatically reducing the pressure in the motor chamber 28.

With reference to FIGURE 3, a modified gas driven hydraulic pump is shown wherein the inertia effects of the reciprocating pistons are neutralized. To accomplish this result, the system includes a second set of motor and pumping piston assemblies which move in a direction opposite to that of the first set of motor and pumping piston assemblies. Thus, the pump includes a second set of opposed stepped diameter cylinders and 20' having piston assemblies 12' and 22 disposed for reciprocable movement therein. The piston assemblies include motor pistons 14 and 24 and pumping pistons 16 and 26', which divide their respective cylinders into motor chambers 18 and 29 and pumping chambers 19 and 29. The motor pistons 14' and 14' are interconnected by a plurality of rods 52 so as to move simultaneously in the same direction.

The pumping chamber 19' is connected by passages 30' and 46' to the inlet and outlet check valves 36 and 46, respectively. The pumping chamber 29' is connected by passages 34 and 42' to inlet and outlet check valves 32 and 44. The motor chamber 18' is connected to the passage 110 and the motor chamber 28' is connected to the passage 108. The pilot valves and reversing valves are controlled by the piston assemblies 12 and 22, as in the first embodiment, the arrangement being such that when gas under pressure is supplied to the motor chamber 18 so as to efiect movement of the pistons 12 and 22 to the right, gas will be supplied to the motor chamber 28' so as to effect movement of the pistons 12 and 22 to the left. Conversely, when the pistons 12 and 22 are moved to the left, the pistons 12 and 22 are moved to the right so as to neutralize the reciprocating inertia effects of the piston assemblies. Operation of the system disclosed in FIGURE 3 is believed to be readily apparent since the control valves are identical to those described in connection with FIGURE 1. The pumping system of FIGURE 3 will, of course, supply hydraulic fluid under pressure in volumes substantially twice that of the system depicted in FIGURE 1.

While the embodiments of the invention as herein disclosed constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A gas driven hydraulic pump including, a first pair of opposed cylinders, a first pair of pistons disposed within said first pair of cylinders and interconnected for simultaneous movement in the same direction, a second pair of opposed cylinders, a second pair of pistons disposed within said second pair of cylinders and interconnected for simultaneous movement in the same direction, each piston dividing its respective cylinder into a motor chamber and a pumping chamber, passage means interconnecting opposed motor chambers of said pairs of cylinders whereby the first and second pair of pistons will move simultaneously in opposite directions, and piston actuated reversing valve means operatively connected to said passage means for controlling the alternate admission and exhaust of gas under pressure to the opposed motor chambers of said pairs of cylinders.

2. A gas driven hydraulic pump including, a first pair of opposed cylinders, a first pair of pistons disposed within said first pair of cylinders and interconnected for simultaneous movement in the same direction, a second pair of opposed cylinders, a second pair of pistons disposed within said second pair of cylinders and interconnected for simultaneous movement in the same direction, each piston dividing its respective cylinder into a motor chamber and a pumping chamber, passage means interconnecting opposed motor chambers of said pairs of cylinders whereby the first and second pair of pistons will move simultaneously in opposite directions, a servo actuated reversing valve operatively connected to said passage means for controlling the alternate admission and exhaust of gas under pressure to the opposed motor chambers of said pairs of cylinders, and a pair of piston actuated pilot valves operatively connected with said reversing valve for controlling the servo actuation thereof, said pilot valves being actuated by one of said pairs of pistons adjacent the stroke ends thereof.

3. A gas driven hydraulic pump including, a first pair of opposed cylinders, a first pair of pistons disposed within said first pair of cylinders and interconnected for simultaneous movement in the same direction, a second pair of opposed cylinders, a second pair of pistons disposed within said second pair of cylinders and interconnected for simultaneous movement in the same direction, each piston dividing its respective cylinder into a motor chamber and a pumping chamber, inlet and outlet check valves communicating with each pumping chamber, passage means interconnecting opposed motor chambers of said pairs of cylinders whereby the first and second pair of pistons will move simultaneously in opposite directions, reversing valve means operatively connected to said passage means for controlling the alternate admission and exhaust of gas under pressure to the opposed motor chambers of said pairs of cylinders, and means operable to acutate said reversing valve means adjacent the stroke ends of said first pair of pistons.

4. A gas driven hydraulic pump including, a first pair of opposed cylinders of stepped diameter, a first pair of pistons having head portions of different diameters mounted for reciprocation within said first pair of cylinders, means interconnecting said first pair of pistons for simultaneous movement in the same direction, a second pair of cylinders of stepped diameter, a second pair of pistons having head portions of different diameter mounted for reciprocation within said second pair of cylinders, means interconnecting said second pair of pistons for simultaneous movement in the same direction, each piston dividing its respective cylinder into a motor chamber and a pumping chamber, passage means interconnecting opposed motor chambers of said pairs of cylinaoravss with said pilot valves for actuating said pilot valves adja-v cent the stroke ends of said first pair of pistons.

References Cited in the file of this patent UNITED STATES PATENTS Mayer Apr. 29, 1941 McCormick Sept. 22, 1942 Schemmel 'July 16, 1957 A "w w 4 

